Docker Import Post-Processor

Type: docker-import

The Packer Docker import post-processor takes an artifact from the docker builder and imports it with Docker locally. This allows you to apply a repository and tag to the image and lets you use the other Docker post-processors such as docker-push to push the image to a registry.

Basic Example

{
  "builders": [
    {
      "type": "docker",
      "image": "ubuntu:18.04",
      "export_path": "party_parrot.tar"
    }
  ],
  "post-processors": [
    {
      "type": "docker-import",
      "repository": "local/ubuntu",
      "tag": "latest"
    }
  ]
}

source "docker" "example" {
    image = "ubuntu:18.04"
    export_path = "party_parrot.tar"
}

build {
  sources = [
    "source.docker.example"
  ]

  post-processor "docker-import" {
    repository = "local/ubuntu"
    tag = "latest"
  }
}

Configuration

The configuration for this post-processor only requires a repository, a tag is optional.

Required:

• repository (string) - The repository of the imported image.

Optional:

• tag (string) - The tag for the imported image. By default this is not set.

• changes (array of strings) - Dockerfile instructions to add to the commit. Example of instructions are CMD, ENTRYPOINT, ENV, and EXPOSE. Example: [ "USER ubuntu", "WORKDIR /app", "EXPOSE 8080" ]

• keep_input_artifact (boolean) - if true, do not delete the source tar after importing it to docker. Defaults to false.

• platform (string) - Set platform if server is multi-platform capable.

Example

An example is shown below, showing only the post-processor configuration:

{
  "type": "docker-import",
  "repository": "hashicorp/packer",
  "tag": "0.7"
}

post-processor "docker-import" {
  repository = "hashicorp/packer"
  tag = "0.7"
}

This example would take the image created by the Docker builder and import it into the local Docker process with a name of hashicorp/packer:0.7.

Following this, you can use the docker-push post-processor to push it to a registry, if you want.

Changing Metadata

Below is an example using the changes argument of the post-processor. This feature allows the tarball metadata to be changed when imported into the Docker environment. It is derived from the docker import --change command line option to Docker.

Example uses of all of the options, assuming one is building an NGINX image from ubuntu as an simple example:

{
  "type": "docker-import",
  "repository": "local/centos6",
  "tag": "latest",
  "changes": [
    "USER www-data",
    "WORKDIR /var/www",
    "ENV HOSTNAME www.example.com",
    "VOLUME /test1 /test2",
    "EXPOSE 80 443",
    "LABEL version=1.0",
    "ONBUILD RUN date",
    "CMD [\"nginx\", \"-g\", \"daemon off;\"]",
    "ENTRYPOINT /var/www/start.sh"
  ]
}

post-processor "docker-import" {
  repository = "local/centos6"
  tag = "latest"
  changes = [
    "USER www-data",
    "WORKDIR /var/www",
    "ENV HOSTNAME www.example.com",
    "VOLUME /test1 /test2",
    "EXPOSE 80 443",
    "LABEL version=1.0",
    "ONBUILD RUN date",
    "CMD [\"nginx\", \"-g\", \"daemon off;\"]",
    "ENTRYPOINT /var/www/start.sh",
  ]
}

Allowed metadata fields that can be changed are:

• CMD
  • String, supports both array (escaped) and string form
  • EX: "CMD [\"nginx\", \"-g\", \"daemon off;\"]"
  • EX: "CMD nginx -g daemon off;"
• ENTRYPOINT
  • String
  • EX: "ENTRYPOINT /var/www/start.sh"
• ENV
  • String, note there is no equal sign:
  • EX: "ENV HOSTNAME www.example.com" not "ENV HOSTNAME=www.example.com"
• EXPOSE
  • String, space separated ports
  • EX: "EXPOSE 80 443"
• LABEL
  • String, space separated key=value pairs
  • EX: "LABEL version=1.0"
• ONBUILD
  • String
  • EX: "ONBUILD RUN date"
• MAINTAINER
  • String, deprecated in Docker version 1.13.0
  • EX: "MAINTAINER NAME"
• USER
  • String
  • EX: "USER USERNAME"
• VOLUME
  • String
  • EX: "VOLUME FROM TO"
• WORKDIR
  • String
  • EX: "WORKDIR PATH"